<!DOCTYPE html>
<html lang="en">

<head>
   <meta charset="utf-8">
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

</head>

<body>
<input type="text" id="username"><input type="checkbox" id="remember">记住我
<script>
    var username = document.querySelector('#username');
    var remember =document.querySelector('#remember');
    if(localStorage.getItem('username')){
        username.value = localStorage.getItem('username');
        remember.checked = true;
    }
    remember.addEventListener('change',function(){
        if(this.checked){
            localStorage.setItem('username',username.value);
        }
        else{
            localStorage.removeItem('username');
        }
    })
</script>

  

    
</body>
</html>